Cathode ray tubes



Jan. 13, 1970 H. L. RATUFEJR 3,489,945

CATHODE RAY TUBES l1 Sheets-Sheet 1 Original Filed April 24, 1965 90% QMN INVENTOR 1970 H. 1.. RATLIFF, JR 3,489,945

GATHODE RAY TUBES Original Filed April 24, 1963 11 Sheets-Sheet 2 INVENTOR Jan. '13, 1970 H, RATLIFF, JR 3,4

GATHODE RAY TUBES Original Filed April 24, l963 ll Sheets-Sheet :5

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CATHODE RAY TUBES Original Filed April 24, 1965 1'1 Sheets-Sheet 5 INVENTOR FIGIZ Jan. 13, 1970 H. RATLIFF, JR 3,489,945

CATHODE RAY TUBES I Original Filed April 24, 1963 ll Sheets-Sheet 6 FIG. 14'

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CATHODE RAY TUBES 11 Sheets-Sheet '2 Original Filed April 24, 1 963 INVE NTOR Jan. 13, 1970 H. L. RATLIFF, JR 3,489,945

CATHODE RAY TUBES Original Filed April 24, 1963 ll Sheets-Sheet B INVENTOR FIG. 25 M i.

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CATHODE RAY TUBES l1 Sheets-Sheet 9 Original Filed April 24, 1963 FIG. 28

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CATHODE RAY TUBES Original Filed April 24, 1963 11 Sheets-Sheet 11 J I r n'm' F mm mm L .1 171v m v L I F wflap m g D INVENTOR United States Patent Ofifice 3,489,945 CATHODE RAY TUBES Harvey L. Ratliff, In, Oxon Hill, Md., assignor to Jetru Inc., Amarillo, Tex.

Continuation of application Ser. No. 505,118, Oct. 18, 1965, which is a division of application Ser. No. 275,411, Apr. 24, 1963. This application Feb. 14, 1967, Ser. No. 624,638

Int. Cl. H01j 31/24 US. Cl. 315-13 2 Claims ABSTRACT OF THE DISCLOSURE A cathode ray tube is disclosed which enables highly resolved wide-angle pictures to be produced by reversing the chromatic aberration and distortion that can be introduced at wide angles of view by some wide-angle oculars.

This is a continuation application of my copending US. application Ser. No. 505,118, filed Oct. 18, 1965, now abandoned which is a divisional application of US. Ser. No. 275,411, filed Apr. 24, 1963 now abandoned. The present invention relates generally to cathode ray tubes. It is contemplated that the tubes are to be used in Wideangle stereoscopic viewing devices described in the parent application Ser. No. 275,411. The cathode ray tubes of the present invention are not limited to the uses described in said parent application, of course.

In wide-angle stereoscopic viewers there is a need for a highly resolved means other than lenticular means to correct for such problems as chromatic aberration, barrel distortion and pin cushion distortion either directly while a moving image is being viewed or to expose film which will be viewed later. The device of the present invention has utility in both of these situations among other situations.

The prior art does not teach a system which corrects for these problems in a non-lenticular manner which is adaptable to extremely wide-angle stereoscopic viewing.

It is the primary object of the present invention to teach a cathode ray tube which will aid in the solution of these problems.

Other objects and advantages of my invention will become more apparent from a study of the following description taken with the accompanying drawings wherein:

FIG. 1 is a side view of a mechanical-electrical-optical unit which illustrates a contemplated embodiment in which the present invention has utility.

FIG. 2 is a rear view of the combination shown in FIG. 1.

FIG. 3 is a front view of the combination shown in FIG. 1.

FIG. 4 diagrammatically shows the optics and some of the electronics involved in a recording process with which the present invention has utility.

FIGS. 58 diagrammatically illustrate some of the electronics usable in conjunction with the present invention.

FIGS. 9 and 10 are enlarged partial sectional views designed to illustrate the type of target used in the contemplated form of the invention.

FIGS. 11 and 12 are elevational views designed to illustrate some of the apparatus used in making the targets of FIGS. 9 and 10.

FIGS. 1316 are partial sectional enlarged views designed to illustrate the steps taken to make the targets of FIGS. 9 and 10.

FIG. 17 is a sectional view of the optical portion of the kinescopic optical viewing device KD of FIG. 1 in which the present invention has a contemplated utility.

3,489,945 Patented Jan. 13, 1970 FIG. 18 is a partial sectional enlarged view of a screen used in on contemplated form of the cathode ray tube of the present invention.

FIG. 19 is a partial sectional view of the apparatus used to make the screen of FIG. 18 and FIG. 22 (2).

FIGS. 20 and 21 are partial sectional enlarged views designed to illustrate the steps taken in making the screen of FIG. 18.

FIG. 22 shows a partial sectional enlarged view designed to illustrate the steps taken in making the screen of FIG. 22 (2).

FIGS. 23 and 24 are broken sectional views of wideangle oculars used in conjunction with illustrations of principles which are basic to the present invention.

FIG. 25 is a sectional view of one contemplated form of a cathode ray tube used in the present invention.

FIG. 26 is a sectional view taken along line 2626 of FIG. 25 in the direction of the arrows.

FIG. 27 is a sectional view of another contemplated form of the cathode ray tube of the present invention.

FIG. 28 is a sectional view taken along line 2828 of FIG. 27 in the direction of the arrows.

FIG. 29 is designed to illustrate some concepts involved in correction for distortion.

FIGS. 3032 diagrammatically illustrate some of the electronic and magnetic functions of the invention.

Referring more particularly to FIGS. 1-3 of the drawings, MR denotes one contemplated embodiment in which the invention has utility. Numeral 32 denotes the tripod assembly which may be of any well known design. The contemplated design has legs 40 and racks 37 on a universal mount. The hand wheel 38 will rotate the system in a horizontal plane and the hand wheel 39 will rotate the system in a vertical plane. On the universal mount is base plate 28, on which the entire system is mounted. The film F is contained on reels, one being in hull 25A and the other being in hull 25B. The film mechanism inside hull 25A, 25B, and 29 functions in a well known manner of the motion picture art. In hull 26 is a right eye view pick up tube which can be constructed on the principle of an image orthicon, or the well known vidicon tube, however, the contemplated embodiment VR (shown more explicitly in FIG. 4) is a simultaneous color pick up tube which will be described more completely later. In hull 27 is a left eye view pick up tube VL which is like VR. The recording technician places his nose in nose guide 35 and looks through lens LE-L with his left eye and LE-R with his right eye. Lenses LE-L and LE'R are designed such that it does not matter whether he wears glasses or not. Light shielding eye guide 33 substantially stops any light from interfering with his view. Lenses LE-L and LE-R are supported by front plate 34. Screen 36 separates the optical portion from the kinescopic portion which will both be described more completely later. Various control knobs and switches will be mounted on control panel 30.

Upon turret 24 is mounted a pair of wide-angle lenses LL and LR placed at the interpupillary distance of 2 and 83 inches apart. Turrent 24 may be rotated to other desirable lenses LL-l and LR-l, or LL-2 and LR-Z by turret control 31 in any well known manner such as a shaft, gear, and chain arrangement (not shown). Lenses on turret 24 may be focused by moving turret mounting plate 23 back and forth in the manner taught by W. R. Smith et al. in Patent No. 2,960,565 issued Nov. 15, 1960 or any other well known manner.

The optical arrangement is schematically illustrated in FIG. 4. Numerals 1L and IR indicate respectively left and right Wide-angle lens systems, which may be of a well known type such as that shown by R. P. Bonnell et al. in Patent No. 3,068,752 in FIG. 4; however, the type contemplated is that shown on pages 58 and 59 in the Oflicial Nikon F and Nikkorex F Manual by the Amphoto Editorial Board, copyright 1962 by American Photographic Book Publishing Co., Inc. printed by The Book Press, Brattleboro, Vt. (Library of Congress Catalog Card No. 62-17655). If either of these lenses are used, however, the diaphragm would be removed to be relocated for the sake of a longer back focus as shown by FIG. 3 of Bonnell et a1. Peripheral rays 21L and 21R respectively and 22L and 22R respectively, and central rays 20L and 20R respectively pass through wide-angle lens systems 1L and 1R respectively, through collector lens systems 2L and 2R respectively and impinge upon beam splitting mirrors 3L and SR respectively; the respective rays which pass through 3L and SR pass through lens systems 4L and 4R respectively which focus them on targets 7L and 7R respectively, after being reflected from highly eflicient mirrors or reflectors 5L and SR respectively and passing though diaphragm 6L and GR respectively; the respective rays, which are reflected from 3L and 3R respectively are reflected from highly eflicient mirrors or reflectors 8L and 8R respectively, pass through focusing lenses 9L and 9R respectively, diaphragms 10L and 10R respectively and are focused by lens system 9L and 9R upon film F at 11L and 11R respectively. Frames 11L and 11R may be side by side in two separate rows or both in one row. Film F is of either a well known black and white or color variety. The film feed and exposure techniques for reproduction not shown or described in this specification are of any operative type well known in the motion picture art. Also any optical, electronic or television techniques not shown or described in this specification are of any operative well known type in any field of electronics or optics.

It is understood, of course, that the film may be used in a manner obvious from my prior copending application S.N. 250,562 filed Jan..10, 1963 after it has been developed. It is also understood of course that if the pick up tubes VL and VR make an angle with the horizontal (as shown in FIGS. l-3) said tubes would be rotated about the axis passing through the center of diaphragms 6L and 6R respectively such that the image would be recorded properly by tubes VL and VR respectively. Tubes VL and VR may be any well known type; however, it is contemplated that they be simultaneous color pick up tubes comprising an evacuated envelope having electron guns mounted in one end thereof. As is well known the electron guns of each tube include a cathode 19L and 19R, control electrode 18L and 18R, one or more accelerating and focusing electrode 17L and 17R,

' and a final accelerating electrode 16L and 16R. Targets 7L and 7R which will be described in more detail later are mounted on the opposite ends of tubes VL and VR to be scanned by electron beams in a manner which will be described in more detail later. The attainment of beam sizes small enough and sweep speeds and scanning (sawtooth) frequencies high enough for applicants system as will be set forth has been taught by others and will therefore, not be set forth herein (i.e. see The Proceedings of The 5th Annual 1963 Electron Beam Symposia, Boston, Library of Congress No. TK 7801, S816 and A Wide-Band Differential Amplifier Oscilloscope Attachment, by A. William Carlson, United States Department of Commerce Oflice Technical Services, June 1955, pp. 9 and 10, FIG. 6).

Means are provided for scanning each electron beam over the surface of targets 7L and 7R which may include The signal from both VL and VR could be taken in the form necessary for a single tri-gun kinescopic optical viewing device in overlapped relationship shown in FIGS. 13, 17, and 25 by using the electronic circuitry schematically illustrated in FIG. 5. Also without the circuitry of FIG. 5 the signals from VL and VR could be taken in the form necessary for a single kinescopic tube designed with a dual tri-gun arrangement focusing on a single screen in an overlapped relationship shown in FIG. 27. Said overlapped relationship may be more clearly described after observation is made of FIG. 17, which will be described in more detail later. The image reproduced for the left eye lies on screen 36 between B and C while the image reproduced for the right eye lies between B and C. Said overlapped relationship stems from the fact that the area of screen 36 between B and C is common to both the right eye view and the left eye view image. This area inherently depends upon the image size and must be distinguished from the entire volume of space which is seen by both eyes and which is inherently independent of the image size.

Referring to FIG. 5 VL and VR represent the same pair of simultaneous color pick up tubes shown in FIG. 4. Preferably in the form of the invention involving FIG. 4 tubes VL and VR have circuitry arranged such that the signals generated by each tube are alternately impressed upon a suitable common amplifier. While this alternate switching may be accomplished in any well known manned it is contemplated to employ a pair of grid controlled tubes which are arranged to pass plate current at regular recurrent spaced intervals one tube being blocked while the other tube is passing current. Thus as shown in FIG. 5 the television impulses generated by left eye view blue sensitive bus bar 41L of VL (see FIGS. 9 and 10) are applied to control grid 104 of a suitable grid controlled tube which is preferably, although not necessary of the screen grid type comprising an electron emitting cathode 106, a control grid 104, a shield-grid 102, and a plate electrode 96. Also the television impulses from left eye view green sensitive bus bar 42L and red sensitive bus bar 43L respectively are applied to similar control grids 92 and 74 respectively of similar grid controlled tubes respectively having electron emitting cathodes 94 and 76 respectively, control grids 92 and 74 respectively shieldgrids 90 and 72 respectively and plate electrodes 84 and 70 respectively. Further the television signals from right eye view blue sensitive bus bars 41R, green sensitive bus bars 42R, and red sensitive bus bars 43R respectively are applied to control grids 105, 93, and 75 respectively in similar grid-controlled tubes having electron emitting cathodes 107, 95, and 77 respectively, control grids 105, 93, and 75 respectively, shield grids 103, 91, and 73 respectively, and plate electrodes 97, 85, 71 respectively. The grid 104 is connected to cathode 106 through the gride biasing resistors 48A and 47A and then to ground through the steady D.C. biasing source 45, it being understood that the cathode 106 is grounded is indicated. A similar grid biasing circuit is provided for grids 92 and 74 respectively traceable through 480 and 48B respectively, through 470 and 47E respectively, through D.C. biasing source 45 to ground and to cathodes 94 and 76 respectively. Also grid biasing circuits are provided for grids 105, 93, and 75 respectively traceable through 48B, 48D, and 48F respectively, through 47B, 47D, and 47F respectively, through D.C. biasing source 45 to ground and to cathodes 107, 95, and 77 respectively. Plate electrodes 96, 84, and 70 respectively are connected each to a suitable source of steady plate potential 98, 86, and 80 respectively, through resistors 99, 87, and 81 respectively. Also plate electrodes 97, 85, 71 respectively are connected each to said steady plate potential 98, 86, and 80 respectively, through said resistors 99, 87, and 81 respectively. Shield-grids 102, 90, and 72 respectively are connected to an intermediate point of DC. supply sources 98, 86, and 80 respectively, through suitable resistors 100, 88, and 78 respectively. Also shield-grids 103, 91, and 73 respectively are connected to said intermediate point of said D.C. supply sources 98, 86, and 80 respectively, through suitable resistors 101, 89, and 79 respectively. The parameters of the above described gridbiasing circuits for each of the above described tubes are chosen so that normally each tube is biased to its plate current cut-ofi. It is desired that the three left eye view sensitive tubes pass current at alternate intervals to the three right eye view sensitive tubes. In order to do this there is provided a pair of grid controlled tubes having cathodes 60, and 61 respectively, grids 56 and 57 respectively and plates 54 and 55 respectively. Said tubes are interconnected with a source of alternating current 44 by a multivibrator circuit arrangement. For this purpose the plate electrodes 54 and 55 respectively are connected through their individual resistors 50 and 51 respectively to a source of steady plate current 46. The control grids 56 and 57 respectively are connected to their cathodes 60 and 61 respectively through leak resistors 58 and 59 respectively. The plate 54 is connected through capacitor 53 to control grid 57, and plate 55 is similarly connected through capacitor 52 to control grid 56. The control grid 56 is also connected through capacitor or condenser 49 to the alternating current source 44.

It is understood that the amplification systems illus trated and describedwith regard to FIG. 5 are schematic in nature and the well known and obvious methods of achieving frequency band-widths suitable for my invention in these amplification systems are utilized therein. Amplification systems for passing such band-widths are attainable (i.e. see The Television Field, by Milton S. Kiver, Television Simplified, sixth edition, copyright 1962 by D. Van Nostrand Company, Inc., pp. 33 and 39.).

Source 44- is syncronized with the line frequency of pick-up tubes VL and VR so that source 44 produces a signal at one-half the line scanning frequency. (That such high frequency syncronization and square or sawtoothwave generation is attainable can be varified by reading the specifications of the Tektronix 105 Generator and the Tektronix 513 Scope or by reference to Carlson as cited above.) The plate 54 is connected through capacitor 68 to point 62 between resistors 47A and 48A, to point 64 between resistors 47C and 48C, and to point 66 between resistors 47E and 48E. Also plate 55 is connected through capacitor 69 to point 63 between resistors 47B and 48B, to point 65 between resistors 47D and 48D, and to point 67 between resistors 47F and 48F. Because of the multivibrator connection between source 44 and the two said tubes, these latter tubes are alternately eflective in passing plate currents. In other words, the voltage conditions on plates 54 and 55 are 180 out of phase as represented respectively by the curve of FIG. 6 and the curve of FIG. 7 and the frequency of the curves of FIGS. 6 and 7 is onehalf of the line scanning frequency represented by the curve of FIG. 8. (Both the wave-forms and frequencies of FIGS. 6, 7, and 8 required for the present invention are attainable as set forth hereinabove.) Consequently, the potential of points 62, 64, and 66 will be 180 out of phase with the potential of points 63, 65, and 67 respectively at any given instant. Therefore, the biasing potential of 104, 92, and 74 plus that of 105, 93, and 75 at any given instant, will be determined by the biasing circuits above described as well as the potential applied through capacitor 68 and 69. Therefore, when grids 104, 92, and 74 are biased below cut-off, grids 105, 93, and 75 are biased above cut-off. Consequently plates 96, 84, and 70 respectively will pass the amplified television currents from blue sensitive bus bar 41L, green sensitive bus bar 42L, and red sensitive bus bar 43L respectively to amplifier 108 during a given scanned line of the image upon target 7L, and when the neXt line of each image upon VL and VR is scanned, grids 104, 92, and 74 respectively are biased below cut-off and grids 105, 93, and 75 respectively are biased above cut-off so that the amplified output from plates 97, 85, and 71 respectively alone are applied to the amplifier 108. By this arrangement, the devices VL and VR may scan an image of a wide-angle stereoscopic action scene continuously, however,. the impulses from the devices VL and VR are alternately effective in controlling the amplifier 108 and since the alternations are synchronized with the line scanning frequency, the net result is that the two images focused on targets 7L and 7R (of FIG. 4) may be formed in the above described overlapped relationship on a single screen of a single kinescopic optical viewing device or on many single screen type kinescopic optical viewing devices.

The signals from amplifier 108 could of course be recorded on tape, transmitted, received, or monitored by many kinescopic optical viewing devices as described in my co-pending application S.N. 250,562, filed Jan. 10, 1963. Also as indicated above, the signals from bus bars 41L, 42L, 43L, 41R, 42R and 43R could all go directly into an amplifier system, to be recorded on tape, monitored by many kinescopic optical viewing devices, or transmitted and received. More detail on these matters will be given later. The primary design, of course, is for these signals to be monitored by KD in order to eliminate doubt as to what is recorded on film F.

Targets 7L and 7R will now be described in detail (see FIGS. 9l6). Elements 109 are red light filtering elements; elements 110 are green light filtering elements; and elements 111 are blue light filtering elements. Strips 112, 113 and 14 are transparent conductive signal strips. Signal strips 112 are formed behind the green filtering elements 110. Signal strips 113 are formed behind the blue filtering elements 111. Signal strips 114 are formed behind the red filtering elements 109. Each signal strip is somewhat longer than the filtering element it is behind. In the case of 7R for example signal strips 13 are electrically connected tobus bars 41R and insulated from bus bars 42R and 43R by filtering elements 111. Signal strips 112 are electrically connected to bus bars 42R and insulated from bus bars 41R and 43R by filtering elements 110. Signal strips 114 are electrically connected to bus bars 43R and insulated from bus bars 41R and 42R by filtering elements 109. For many of the details of how targets 7L and 7R are made, reference is made to Paent No. 2,745,773 issued to Paul K. Weimer, May 15, 1956. The target of the present invention differs from that of Weirner however. For reception as shown in FIG. 25 it is desirable in this invention that there are, by way of example, around 16,000 total effective scan lines in each of the tubes VL and VR if there Is to be 8,000 scan lines for each eye view. For reception as shown in FIG. 27 only 8,000 total scans in each tube VL and VR would be required in either the horizontal or vertical direction. This of course would mean that there would need to be from 8,000l6,000 blue filtering elements 111, 8,000-16,000 green filtering elements 110, and 8,000-16,000 red filtering elements 109, and of course a total number of 24,00048,000 signal strips. This large number of total scan lines of course is determined by the fact that it is desirable that each scan line subtends little more than an angle of one minute at the eye of a viewing observer. If the angle of view for each eye in the kinescopic optical viewing device of FIG. 17 is and the total number of scan lines effective for each eye is 8,000 (as indicated above), it is calculated that:

(160) (60 minures/degrees) 1.20 minutes 8,000 scan lines scan line Therefore, there are 1.2 minutes per scan line, which is considered small enough to make the scan lines virtually unnoticeable and to ofier the potential of resolving power approaching that of the human eye. However, the Nikon Flsheye lens does not offer this great resolving power; so bandwidths this great (i.e. 8,000 elements in each strip per 5 inches) are not necessary for pleasing re-creations, and the scan lines do not even have to be this small for operability. In fact the resolving power of the Nikon Fisheye lens is known to be only 250 lines per mm. Since the image is only a 24 mm. image, each resolvable element is representative of (24 250/60 l80=1/1.8) 1.8 minutes at the eye of a viewing observer, which is still further increased due to the resolving power of the film (if film is used thenewith).

It is of course desirable, but not necessary, that each pick-up tube VL and VR is as small as is practical; so a method for making the filtering elements 109, 110, and 111 and the signal strips 112, 113, and 114 as small as is practical is desired but not necessary as long as the total number of scan lines is sufliciently great.

It is well known that platinum can be drawn into wires only 0.00003 inch in diameter 1/ 33,333 inch). It is also well known that the tensile strength of drawn platinum is 50,000 pounds per square inch. It is also well known that since Rowlands screw of 1882, it has become possible to accurately measure distances as small as 1/ 15,000 inch (see pp. 342 and 343 of Fundamentals of Optics, by Jenkins and White, 3rd edition, copyright 1957 by McGraw-Hill Book Company, Inc.). It is also well known that with the aid of this precise screw, diamond points can rule as many as 15,000 grooves per inch on a metal surface.

For the contemplated method of making targets 7L and 7R desirably small for my invention, fixed mask 32 (of FIGS. 6 and 7 of Weimer) is replaced by fixed mask 32X of FIGS. 11 and 12 in this application. Reference is now made to FIGS. 11 and 12. There are 8,000 grooves (135 of FIG. 15) per inch on each of cylinders 49X and 50X. If targets 7L and 7R are each designed for reception in the kinescopic optical viewing device of FIG. 27, work piece 117 could be only slightly larger than one inch than one inch by one inch and of any desirable thickness. If however 7L and 7R are each designed for reception in the kinescopic optical viewing device of FIG. 25, work piece 117 would need to be only slightly larger than two inches by three and one-tenth inches and of any desirable thickness. Platinum or other desirable wire of 0.0000835 inch (l/l2,000 inch) diameter is drawn and spooled on spool 122 (see FIG. 12) in a well known manner. In device MD the pitch of the threads of screws 124, 127, and 130 and the threads of heads 126 and 131 are designed such that every time element 32X is rotated one revolution by driving means 134 (which could be any well known type of driving means), eye 125 moves along screw 124 a distance of 1/8,000 inch. It is understood of course, that screw 124 is the precision type screw described above as are the threads of 125. Rod 128 may be slipped out of base 133 to allow eye 125 to be positioned on screw 124 so as to correspond to the farthest left groove of 49X and 50X. Wire 48X is threaded from spool 122 through eye 125 and fastened to cylinder 49X (both 49X and 50X are made of the same material that high quality reflecting diffracting gratings are made of). A braking means 123 is held on spool 122 in order that the tension in wire 48X will force it in the smallest point of eye 125 and keep it precisely there. Now element 32X is rotated by drive means 134 supported in post 132. This in turn rotates screw 130 which rotates head 131 which rotates screw 127 (which is supported by post 129). Screw 127 rotates head 126, which in turn rotates screw 124. Screw 124 causes translation of eye 125 which causes translation of wire 48X to the next adjacent groove (135 of FIG. 15). In this way 8,000 strands per inch of wire having a diameter of 0.0000835 inch spaced 0.0000417 inch apart are wound around cylinders 49X and 50X. Wires 48X are then fastened to cylinders 49X and 50X by soldering or some other desirable method. As shown in FIG. 11, the top layer of wires 48X is removed leaving only the bottom layer. Any desirable tension may be placed upon wires 48X by means of worm gear arrangement 118, 119, 120, and 121 of FIG. 11 which rotates screws 52X in 49X and post 53X. For precise control, screws 52X must be of the precision described above, of course. In the apparatus.

of Weimer micrometer screw (66 of FIG. 9 of Weimer) must be, for this invention, of the precision described above and gears (67 and 68 of FIG. 5 of Weimer) must be of the Worm gear type such as 126 and 127 of FIG. 12 of the present invention. Also rod (69 of FIG. 5 of Weimer) must be connected to another worm gear arrangement such as 130 and 131 of the present invention. In a manner obvious from Weimer, red filtering elements are evaporated on work piece 117 of FIG. 13 (a). Next work piece 117 is moved to the right 0.0000417 inch by the precise micrometer screw described above (see FIG. l3(b)). Then the green filtering elements are evaporated onto work piece 117 in a manner "obvious from WeimenNext work piece 117 is moved to- I r the right 0.0000417 inch by the precise micrometer screw described above. Now the blue filtering elements 111 are evaporated onto work piece 117 in a manner obvious from Weimer.

Now wires 48X shown in FIG. 14 are wound around another element 32X with the aid of device MD, in the manner described above. Wires 48X have a diameter of 0.0000952 inch and since there are 8,000 wires per inch, they are spaced apart 0.0000300 inch.

With the aid of red light passing filter (103 of FIG. 1 of Weimer) and photocell (101 of FIG. 1 of Weimer), work piece 117 of FIG. 14(a) is moved until a very slight movement of work piece 117 to the right causes no change in the reading of (102 of FIG. 1 of Weimer) while the slightest movement to the left of 117 causes a decrease in the reading of (102 of FIG. 1 of Weimer). Under these conditions the left edges of wires 48X are in alignment with the lines of abutment between red filtering elements 109 and blue filtering elements 111. At this point work piece 117 is moved to the right 0.0000117 inch as nearly as possible.

In a manner obvious from Weimer, red signal strips 114 are evaporated onto red filtering elements 109 such as to extend to make electrical contact with red bus bars 43R or 43L. Now work piece 117 is moved 0.0000417 inch to the right and green signal strips 113 are evaporated onto green filtering elements 110 such as to extend to make electrical contact with green bus bars 42R or 42L. Now work piece 117 is moved 0.0000417 inch to the right and blue signal strips are evaporated onto blue filtering elements 111 such as to extend to make electrical contact with blue bus bars 41R or 41L whichever the case may be. In this way target 7R and 7L may be made to a very small size which is desired but not necessary.

Of course the photosensitive material 115 (such as red antimony sulfide) of FIGS. 10 and 16 may be formed as taught by Weimer. It may prove desirable to insulate each of the three signal strips 112, 113, and 114 from each other by an insulating material (see 136 of FIG. 16) such as zinc sulfide in a manner obvious from the above description.

At this point the kinescopic optical viewing device KD of FIG. 1 will be described in detail. It is here pointed out that this device KD may be uesd as the cathode ray tube optical viewing device CV of FIG. 6 of my prior application S.N. 250,562 cited above.

Reference is made to FIG. 17. The left and right eyes of the viewing observer are guided to positions A and A respectively by the nose guide 35 (of FIG. 2) and face guiding eye shield (of FIGS. 1 and 17). At position A said left eye has a wide angle of view GAF and said right eye has a wide angle of view GAF'. In order to form an image of angle GAF an image if formed on phosphorescent or fluorescent layer 139 of screen 36 having peripheral rays emitted which originate at points B and C. A ray originating at C passes from fluorescent layer 139 through optical means 138 (which precludes or helps to preclude any rays originating at point C or any left eye View rays from reaching point A) through transparent supporting means 137, to point E on lens LE-L (where it is bent toward point G), through LE-L, through optical element 140, to point G (where it is bent toward A), to point A. By similar ray tracing it is obvious that an image formed having a diameter BC (in the horizontal and vertical plane) would appear to have an angle of view of GAF (in the horizontal and vertical plane). The same obviously applies to the right eye view image having a diameter BC'.

It is here pointed out that a design object is that nose guide 35 and face guiding eye shield 33 are such that a person of normal vision while wearing spectacles will be comfortable while viewing into KD as well as a person of normal vision without spectacles. Further screen 36 and lenses LE-L and LE-R may, of course, be made adjustable by well known methods (for example those taught by M. L. Heilig in Patent No. 2,955,156 issued Oct. 4, 1960).

Referring more particularly to FIG. 18 for a detailed description of the contemplated screen used in the present invention (see 36 of FIG. 27). First optical means 138 will be described in detail. It may be of form 138(a) and 138(b) of FIG. 18 working in conjunction with polarizing filters at the oculars. Also it may be of the form 138(0) shown in FIG. 22(b). Elements 138(a) and 138( b) are light polarizing elements having their axis of polarization rotated 90 degrees from each other. Filters (such as 140 and 141 of said 275,411) are also polarized. Filter 140 has an axis of polarization substantially identical to that of elements 138(11). Filter 141 has an axis of polarization which is rotated 90 degrees from that of 140 and which is substantially identical to those of elements 138(1)). How elements 138(0) function is explained in FIG. 14 of my above cited co-pending application 250,562, filed Jan. 10, 1963.

Only as by way of example, if screen 36 is to be consistent with the example given of targets 7L and 7R the following must be true: If the scan lines are horizontal, there must be a total of 16,000 scan lines (8,000 for each eye). It is understood, of course, that under some of the parameters of this invention the scanning must be vertical for the invention to work. If the scan lines are vertical, there must be 8,000 scan lines for each eye, but the center of each of these 8,000 scan lines for each eye is displaced the inter-pupillary distance of 2% so if KD is designed such that screen 36 will be 7 inches wide, each of the 8,000 scan lines must have a combined width of (7 2 (2)/2=4 Therefore, there would be: 8,000/ 47 :1805 scan lines per inch for each eye and 3610 scan lines per inch. Therefore, for the above design there would be 25,270 total vertical scan lines on a 7" screen, when the tube of FIG. 25 is used. Obviously, part of these 25,270 vertical scan lines would have no velocity modulation; thereby producing no image on screen 36. Only 16,000 of these scan lines are effective in producing an image.

The point is that there is approximately 1 line for each minute of view or 60 lines for each degree of view. It is well known that wide-angle images go even below 120 down to even as low as 80 in their angular field coverage, to still be classified as wide-angle images and that narrow angle images have an angular field between 8 and 45 as a rule. Consistancy with the previous image of 1.2 minute per scan line will clearly reveal that 120 corresponds to 6,000 total scan lines.

As stated hereinabove this sawtooth vertical scanning is only by way of example. It is well known that spiral scanning is more easily accomplished. That spiral scanning is an obvious alternative can be verified by page 14 of Kiver, cited hereinabove. It is well known that spiral scanning is achieved by sinusoidal signals which are much more easily generated than sawtooth signals. As is stated in the parent case, mask 142 assures that the proper electron beam strikes the proper phosphorescent elements;

otherwise, it would be impossible to expose only certain areas with transmitter 150(a).

At this point a contemplated method of making both basic forms of screen 36 will be set forth in detail. First the forms of FIGS. 20 and 21 will be described. By way of example it will be assumed that a 7 x 4 screen designed for horizontal scanning is desired. Since consistency with previous examples requires screen 36 to have 3,610 scan lines per inch, there must be 10,830 fluorescent elements 139 (3,610 of 139(a), 3,610 of 139(0), and 3,610 of 139(6)) Per inch. Wires 142 (see FIG. 19) having a diameter of about 0.0001844 inch are wound around masking frame 147 by use of the device of FIG. 12 or any well known method. Frame 147 having been grooved with 3,610 grooves per inch in the manner described above. Therefore wires 142 are spaced apart about 0.0000922 inch. Light rods or transmitters 150(a), 150 (b) and 159(0) are placed in identically the same positions which will be occupied by the blue gun, green gun, and red gun respectively at a later date. Refracting means 149, which may be three separate diverging lenses, is designed to provide a means of correcting for the position of the screen by having refracting characteristics substantially equivalent to the deflection characteristic of the electron lens used later in the tube. However, it is not necessary to have refracting means 149, any well known method of obtaining exposures of high resolution may be used. Wires 146 are wound around a frame (which is not shown) by the device of FIG. 12, or the like. Said frame has been grooved with 1,805 grooves per inch in the manner described above. Wires 146 have a diameter of about 0.000276 inch and are therefore spaced apart about 0.000276 inch. Said frame for wires 146 is made precisely adjustable by a micrometer screw arrangement such as the one described above. At this point work piece 137 is rigidly held by frame 148 in any well known manner. Light rod 150(a) is illuminated by cylindrical lamp 151(a). Mask 146 is moved to the left until full illumination is measured by microammeter 145 reading current from phototube 144 (which works in conjunction with collimator 143). At this point mask 146 is moved back to the left, which causes an immediate drop in the reading of 145. Now mask 146 is cautiously moved back to the left by the worm gear arrangement described above and stopped at the instant full illumination is indicated by microammeter 145. Masking support 147 is rigidly attached to work piece 137 in any well known manner. The internal surface of work piece 137 is coated with a substantially transparent radiant energy sensitive substance 152 of FIG. 20(a) such as the light sensitive material polyvinyl alcohol sensitized with ammonium dichromate. This coating may be applied by flowing, spraying. or other similar fluid depositing methods. At this point work piece 137 is rigidly held by frame 148 in any well known manner within a tolerance much less than the distance between light rods 150(a), (b), and (0). Now coating 152 is exposed to the light from all three light rods 150(a), 150(1)), and 159(0) illuminated by cvlindrical lamps 151(a), 151(k), and. 151(0) respectively. The exposed areas become hardened and adhere to workpiece 137. Next a developing fluid such as deionized water is applied to the work piece to remove the unhardened areas and to produce a series: of bars or strips approximately 0.0002766 inch wide as shown in FIG. 20( b). At this point a radiant energy sensitive layer 153 having no crystals and being substantially transparent such as polyvinyl alcohol sensitized with ammonium dichromate is placed in a chamber formed by walls 155 and wedging elements 156 in any suitable fashion. Next to the layer 153 as shown in FIG. 20(0) is placed a layer 154, preferably relatively thin, of material containing ultramicroscopie polarizing crystals (such as herapathite). Next to this layer and above it is placed a third layer 153' of the same substance as layer 153. An opening between wedging elements 156 has dimensions substantially similar to a cross-section of layer 154 behind the wedging elements) and is located adjacent to that layer. Means are provided for extruding the material through said opening. In this manner layer 154 is subjected only to the forces of stretch and not to the forces of shear, so that the said ultramicroscopic polarizing crystals are aligned substantially parallel. Therefore, layer 154 becomes dichroic. It is understood of course that only beta type crystals are used or that only alpha type, but not both types for the well known reasons. By way of example layer, 154 is extruded perpendicular to strips 152 as shown in FIG. 20(0). An extra layer of radiant energy sensitive material 157 may or may not be put on as is desired (see FIG. 20(d)). At this point work piece '137 is placed back on frame 148 within the above stated tolerance limits. Now wires 146 are moved either to the left or the right 0.0002766 inch by said micrometer screw. Now conjugately and alternately related strips approximately 0.0002766 inch wide are now exposed (by all three light rods) and developed as shown in FIG. 20(0).

At this point another polarizing layer 159 is extruded as described above, with the following exception: Layer 159 is extruded parallel to said strips 152, not perpendicular as shown in FIG. 20(0). Layer 158 and 158' would be the lower and upper light sensitive sandwiching layers. Therefore, obviously, the axis of polarization of strips 159 is rotated 90 degrees from the axis of polarization of strips 154. Also extra radiant energy sensitive layer 160 may or may not be placed upon layer 158'.

Now work piece 137 is placed rigidly upon frame 148 as above, and wires 146 are moved about 0.0002766 inch in either direction. The conjugately and alternately related polarizing strips 159 are exposed and developed as shown in FIG. 20(g). Now another coating of radiant energy sensitive material 161 is sprayed or placed upon the work piece and exposed and developed in the above described manner resulting in FIG. 21(a) if layers 157 and 160 are desired and in FIG. 21(b) if layers 157 and 160. are not desired. Obviously 138(a) consists of 158, 159, and 158; and 138(1)) consists of 153', 154, and 153.

At this point mask 146 is removed. A slurry 139(1)) of green phosphor material such as zinc orthosilicate and a suitable radiant energy sensitive material is sprayed or otherwise placed upon work piece 137 as shown in FIG. 21(0). Now work piece 137 is rigidly placed upon frame 148 as above and green light red radiating white light 150(b) illuminated by 151(b) exposes only the areas the green gun of FIG. 25 is to make fluoresce later. Now these areas are developed by the application of any desirable developing fluid such as deionized water to remove the unhardened areas, as above, resulting in the configuration shown in FIG. 21(d). In similar manner red phosphor 139(0) and blue phosphor 139(a) being for example Zinc phosphate and zinc sulfide respectively, each sensitized with a suitable radiant energy sensitive material, are exposed by light rods 150(0) and 150(a) respectively and developed as above.

Now the form of FIG. 22 will be described. In most situations this form requires that the scanning is vertical; therefore by way of example vertical scanning will be assumed and the same number of scan lines per inch will be assumed. Therefore the diameter-s of wires 142 and wires 146 are the same as before. However, there would obviously be more and each would be shorter. In other respects the apparatus of FIG. 19 is the same as before. Now some opaque radiant energy sensitive material 138(0) (such as polyvinyl alcohol having randomly dispersed herapathite crystals within it and being sensitized with ammonium dichromate) is flowed or otherwise placed upon work piece 137 as shown in FIG. 22(a) Now mask 146 is oriented as described above such that a viewing observer later can see only the right eye view blue, green, and red phosphor elements (139(a), 139(b), and 139(0)) with his right eye and the left eye view blue, green and red phosphor elements with his left eye.

12 At this point the proper areas are exposed by all three light rods and developed as above to result in FIG. 22(b). Now as many layers 162 and 163 of transparent radiant energy sensitive material may be applied and developed as required for proper function shown in FIG. 14 of my above cited co-pending application 250,562 and shown in FIG. 22(0) for example. Green, red, and blue phosphors are placed upon layer 163 in the manner described above resulting in FIGS. 22(d) and 22(e).

In extremely wide angle stereoscopic kinescopic optical viewing devices such as the one of this invention, chromatic aberration is, of course, a problem. A method of correcting for chromatic aberration is, therefore, obviously desirable. In KD of FIG. 1, the optical effect of chromatic aberration upon a viewing observer may be explained by reference to FIG. 23. As far as the eye of a viewing observer is concerned green gun beam GG, blue gun beam BG, and red gun beam RG all converge at a single spot upon screen 36. Therefore, in explaining FIG. 23, that said beams do converge at one spot upon screen 36 can be assumed. Green rays, blue rays, and red rays leave this spot to pass through lens LE-L (or of course LE-R). At LE-L the rays are bent as shown. The blue rays are bent the most, the green rays are bent next to the most, and the red rays are bent the least so that when these rays pass the lens -1L-L of the left eye of the viewing observer, they cannot all three focus on the retina 164 of his eye. These rays focus on three different planes BP, GP, and RP as shown. If the eye focuses the green rays on the retina 164, the plane of focus of the blue rays BP will be in front, and the plane of focus of the red rays RP will be to the rear of retina 164. The axis of lens LE-L and the left eye view of screen 36 will now be defined as a line passing through the center of lens LE-L and the center of the left eye view on screen 36. It is here pointed out, of course, that near said axis, there will be only negligible chromatic aberration. As the spots from which light rays originate upon screen 36- are displaced in any perpendicular direction from said axis, chromatic aberration increases. In other words the amount of chromatic aberration is a direct function of the displacement distance between the gum convergence spot and the center of the left eye view on screen 36 (in the case of the left eye for example).

One way to correct for chromatic aberration may be explained by reference to FIG. 24. If it is possible to cause the beam from the blue gun to strike said screen 36 at a spot slightly further from said axis than the beam from the green gun does, and to cause the beam from the green gun to strike said screen 36 at a spot slightly further from said axis than the beam from the red gun does to form three separate chromatic rings in a controlled manner, chromatic aberration could be corrected for as shown in FIG. 24. All the time this is going on, mask 142 allows the beam from the blue gun to strike only the blue phosphor elements 139(0) of FIGS. 18 and 22, the beam from the green gun to strike only the green phosphor elements 139(b) of FIGS. 18 and 22, and the beam from the red gun to strike only the red phosphor elements 139(0) and of course elements 138 of FIGS. 18, 20, 21, and 22 make it impossible for the incorrect rays to reach either eye of the viewing observer. Blue light rays leaving the phosphor element energized by the blue gun beam are bent the most as shown in FIG. 24, but since they originate at a point further from said axis than the green light rays leaving the phosphor element energized by the green gun beam, lens LEL bands the blue rays enough more that lens 1LL of the viewing observers eye may focus them both on his retina 164 at the same instant. With the situation as shown in FIG. 24 obvious reasoning shows that said lens 1L-L can focus the blue, green, and red light rays, all on said retina. 164 at the same time. Therefore a means must be devised which will cause said three beams to converge as they normally would at said axis (the center of the right eye view on screen 36), but which will cause displacement between said beams at the same instant upon screen 36 when they are away from said axis in any direction. Said displacement between said beams would be a direct function of the distance said beams strike screen 36 from said axis.

It is well known that certain metals such as iron have a greater magnetic permeability than air, and that there are ways to increase or decrease the magnetic permeability in a given area by the use of such metals. A contemplated method of correcting for chromatic aberration may now be explained by reference to FIGS. 27 and 28. Tube 178 consists of an evacuated envelope containing two sets of three guns. Each gun, of course, consists of a heater, a cathode, a control grid (172L and 172R), an accelerating (or screen) grid (173L and 173R), a focusing electrode (174L and 174R), and a converging electrode (175L and 175R) as shown in FIG. 27. Placed just in front of said electrodes 175L and 175R toward screen 36 are two deflection yokes 176L and 176R. In the center of each deflection yoke is placed a chromatic aberration correcting element 177L and 177R respectively. Elements 177L and 177R correct for chromatic aberration by placing the greatest amount of magnetic permeability around the blue gun beam BG (of FIG. 28), the next greatrest amount of magnetic permeability around the green gun beam GG, and the least amount of magnetic permeability around the red gun beam RG. This magnetic permeability is regulated such as to obtain the most desirable correction for chromatic aberration. One way of doing this is to place magnetically permeable metal cylinders symetrically around the central path of BG, GG, and RG with the thickness greatest around BG, next to the greatest around GG, and least around RG as shown in FIG. 28.

It is obvious that difiiculties would arise when trying to use this principle in tube 166 of FIGS. 25 and 26 in the plane of horizontal deflection. However, the chromatic aberration may be corrected in the plane of vertical deflection by varying magnetic permeability effected by only the vertical deflection coils 167V and 167V as shown in FIG. 26 by 165B, 165G, and 165R as shown.

Depending upon the type of Wide angle lenses (LR and LL of FIGS. 14) used and the type of viewing lenses (LE-L and LE-R of FIGS. 2 and 17) used, either pincushion distortion or barrel distortion may or may not be a problem. In order to make clear that applicant is referring to the well known concept of barrel distortion and pincushion distortion, reference is made to FIG. 29. FIG. 29(a) shows a view which has no distortion; FIG. 29(b) shows a view which has barrel distortion; and FIG. 29(0) shows a view which has pincushion distortion. It the combination of lenses LR, LL, LE-L, and LE-R produce the cflect of barrel distortion for each eye of the viewing observer, if would be desirable to produce pincushion distortion electronically to a suflicient degree to cause the viewing observer to see no distortion. Of course pincushion distortion would need to be electronically corrected in the obvious opposite manner.

It is well known that curvilinear current impulses such as those shown in FIG. 31(b) may be developed and synchronized with a well known saw tooth scanning current impulse such as that shown in FIG. 31(a).

Reference is now made to FIG. 30. A signal voltage EH is developed and synchronized with EV in a well known manner and placed across terminals T1 and T2. Also a signal voltage EV is developed and synchronized with EH and placed across terminals T3 and T4. A form of the well known vertical electromagnetic'deflection voltage EV is placed across terminals TS and T-6, and a form of the well known horizontal electromagneticdeflection voltage EH is placed across terminals T-7 and T8. If voltages EH and EV were disconnected from the circuit of FIG. 30, voltages EV and EH would generate currents 1V and 1H respectively of FIGS. 31(11) and 31(d) respectively rather than currents 1V and 1H respectively of FIG. 30. By way of example the frequency of EH and of course 1H is 30 cycles per second (in order to hold down the well known flicker). In order to be consistent with the parameters described above, we will say that there must be 8,000 vertical scans per horizontal scan. Therefore the frequency of EV and of course 1V is 240,000 cycles per second. Therefore, obviously the time scale for curves (a), (b), and (c) of FIG. 31 indicated by T is different than the time scale for curves (d) and (e) of FIG. 31 indicated by T. Of course EV and EH would be synchronized in a well known manner. If voltages EH and EV wer disconnected from the circuit of FIG. 30, voltages EH would generate current 1H or its reciprocal 1H of FIGS. 14(12) and 14(0) respectively whichever is desirable. Also voltage EV would generate currents IV,,' (of FIG. 31(e)) or its reciprocal (not shown) whichever is desirable.

Electromagnetic-deflection coils 176H, 176H'. 176V, and 176V of FIG. 28 (being of any desirable well known type) are shown schematically in FIG. 30. Coils 176H', 176V, 176H, and 176V are shunted by resistors 179, 180, 181. and 182 respectively in order to damp quickly any oscillation that might be set up because of the distributed capacitance inherent in deflection coils.

The signal placed across T5 and T-6 is traceable from TS through coil 176V which is shunted by resistor 180, through coil 176V which is shunted by resistor 182, to T6 which is grounded, through the transformer coil of signal source EV (not shown), and back to TS.

The signal placed across T7 and T8 is traceable from T7 through coil 176H', which is shunted by resistor 179, through coil 176H which is shunted by resistor 181, to T8 which is grounded, through the transformer coil of signal source EH (not shown), and back to T-7.

The signal placed across T-1 and T-2 is traceable from T-1 to terminal 184. At terminal 184 said signal goes two paths at the same instant. The first path is from terminal 184 through coil 176H' which is shunted by 179, to terminal T7, through the transformer coil described above, through ground, to TZ, through signal source EH and back to T-1. The second path is from terminal 184 through coil 176H which is shunted by 181, to T8. through ground, to T-2, through signal source EH and back to T-l.

The signal placed across T3 and T4 is traceable from T3 to terminal 183. At terminal 183 said signal goes two paths at the same instant. The first path is from 183 through coil 176V which is shunted by resistor 180, to terminal T-S through the transformer coil of EV (not shown), to terminal T6, through ground. to terminal T-4, through signal source EV and back to T3. The second path is from 183 through coil 176V which is shunted by resistor 182, to terminal T-6, through ground to T4 through signal source EV and back to T3.

Now reference is made to FIGS. 28 and 30. Since the force on traveling electrons in a magnetic field is at right angles to both the direction of motion and the lines of the field, coils 176V and 176V deflect the electron beams BG, GG, and RG in vertical planes and coils 176H and 176H' deflect the electron beams BG, GG, and RG in horizontal planes.

Because of the circuitry set forth above, the current developed by EH causes the magnetic flux lines produced by coil 176H to force beams BG, GG and RG to the right when, at the same instant, the magnetic flux lines produced by coil 1761-1 are forcing beams BG, GG and RG to the right. Also this current causes the magnetic flux lines produced by coil 176H' to force beams BG, GG and RG to the left when at the same instant the magnetic flux lines produced by coil 176H is forcing beams BG, GG and RG to the left. Therefore. the current developed by EH causes horizontal scanning in the well known sawtooth manner. For analogous reasons the 15 current developed by EV causes vertical scanning in the well known sawtooth manner.

However, the current developed by EH causes the magnetic flux line produced by coil 176H to force beams BG, GG, and RG to the right when at the same instant the magnetic flux lines produced by coil 176H is forcing beams BG, GG, and RG to the left. When the flux lines surrounding beams BG, GG, and RG produced by coil 176H are exactly as strong as the flux lines surrounding beams BG, GG, and RG and produced by 176H the resultant force is of course zero and the current developed by EH has no effect. However, when the flux lines surrounding any one or all of said beams and produced by one coil are stronger than those surrounding any one orall of said'beams and produced by the other coil, the current developed by EH obviously has a definite effect. Since beam BG in its neutral position is closer to coils 176H' and 176V than 176H and 176V, the magnetic permeability to the right of and below BG should be made greater than that to the left of and above BG (for example by placing more magnetically permeable metal to the right of and below BG). In a similar manner the magnetic permeability surrounding GG and RG should be altered such that when the three beams converge at a spot on screen 36 and also the axis of the center of either the right eye view or left eye view described above, the current developed by either EH or EV has no efiect on beams BG, GG, or RG.

In this situation, the current developed by EH has its greatest effect when beams RG, GG, and RG are the closest to either 176H' or 176H. Likewise, the current developed by EV has its greatest effect when beams BG, GG, and RG are closest to either 176V or 17 6V. Therefore, depending upon Whether the current developed by EH takes the form 1H of FIG. 31(1)) or its reciprocal 1H,," of FIG. 31(c) and Whether the current developed by EV takes the form 1V of FIG. 31(e) or its reciprocal, either pincushion or barrel distortion may be corrected by EH and EV applied in the above described manner.

Since the manufacture of metal elements which cause precisely the magnetic permeability for use in the above described methods of correcting for chromatic aberration, pincushion distortion, and barrel distortion is expensive, it is desirable to devise a method of correcting these difliculties which will not require precise manufacturing. A device for doing this is schematically illustrated in FIG. 32.

Signal source EV is connected across terminals 185 and 189 in such manner as to develop a much weaker signal across potentiometers 205 and 206 than it does across terminals T-5 and T-6 (of FIG. 30). This of course allows the signal across terminals 186 and 187 and the signal across terminals 188 and 189 to be varied. Terminals 186 and 187 are connected across coil 177V as shown. Likewise terminals 188 and 189 are connected across coil 177V. By way of example these connections are made such that the magnetic flux lines created by 177V and 177V are in the same direction at any instant as the corresponding flux lines created by 176V and 176V respectively. Of course this means that current developed by EV would be running the same direction at any corresponding point of both coils 177V and 177V at the same instant of time. Of course the number .of loops in coils 177V and 177V would be much less than the number of loops in coils 176V and 176V. In a similar manner signal source EH is placed across series potentiometers 207 and 208 at terminals 190 and 194. Also potentiometer terminals 191 and 192 are connected across coil 177H' and potentiometer terminals 193 and 194 are connected across coil 177H. To be consistent with the example set forth above, these connections are made such that, the magnetic flux lines created by 177H' and 177H are in the same direction at any instant as the corresponding flux lines created by 176H and 176H respectively.

This, .of course, also means that current developed by EH would be running the same direction at any corresponding point of both coils 177H and 177H at the same instant of time. The number of loops in coils 177H' and 177H would also be correspondingly less than those in 17611 and 176. The type of current developed by the voltage across potentiometers 205 and 206 would of course be of the form shown in FIG. 31(a) as nearly as possible and the type of current developed across potentiometers 207 and 208 would of course be of the form shown in FIG. 31(d) as nearly as possible.

Signal source EV is connected across terminals 204 and 200 in such a manner as to develop a much weaker signal voltage across potentiometers 211 and 212 than it does across. terminals T73. and LE-4. (of FIG.,,30). WTer-M minals 203 and 204 are connected across coil 177V and terminals 201 and 202 are connected across coil 177V. To be consistent with the example set forth above, these connections are made such that the magnetic flux lines created by 177V and 177V are in the same direction at any instant as the corresponding flux lines created by 176V and 176V respectively. This, of course, means that current developed by EV would be running the opposite direction at any corresponding point of both coils 177V and 177V at the same instant of time. Likewise signal source EH is connected across terminals 196 and 199 in such manner as to develop a much weaker signal voltage across potentiometers 209 and 210 than it does across terminals T-1 and T2 (of FIG. 30). Terminals and 197 are connected across coil 177H and terminals 198 and 199 are connected across coil 177H. To be consistent with the example set forth above, these connections are made such that the magnetic flux lines created by 177H' and 177H are in the same direction at any instant as the corresponding flux lines created by 176H' and 176H respectively. This also means that current developed by EH would be running the opposite direction at any corresponding point of both coils 177H and 177H at the same instant of time.

Obviously to correct for chromatic aberration each of the six potentiometers that would be required in the device .of FIG. 27 corresponding to 205 of FIG. 32 and each of the six corresponding to 206 of FIG. 32 would be set to give BG (of FIG. 28) the greatest amplitude (more than GG) and R6 (of FIG. 28) the least amplitude (less than GG). These amplitudes would of course be such as to give the most desirable correction for chromatic aberration. Likewise each of the six potentiometers corresponding to 207 of FIG. 32 and each of the six corresponding to 208 of FIG. 32 would be set to give BG (of FIG. 28) the greatest amplitude and RG the least amplitude so as to give the most desirable correction for chromatic aberration.

Also each of the six potentiometers corresponding to 209 are set to correct for the fact that BG, GG, and RG are not at the same distance from coils 176V, 176V, 176H', and 176H at any same instant of time, as are the six potentiometers corresponding to 210, the six cor responding to 211, and the six corresponding to 212.

As a result of the above set forth electronic arrangement, correcting elements 177 (of FIG. 27) do not have to be precisely manufactured, It is here pointed out that when these various corrections exist, mask 142 still allows BG, GG, and RG to strike only the phosphorescent elements 139 that they are each supposed to strike (BG strikes only 139(a), GG strikes only 139(b), and RG strikes only 139(0)). Also mask 142 allows the beams from the right eye gun to strike only the elements the right eye will see and beams from the left eye gun to strike only the elements the left eye will see.

While the invention has been disclosed and described in some detail in the drawings and foregoing description, they are to be considered as illustrative and not restrictive in character, as other modifications may readily suggest themselves to persons skilled in the art and within the broad scope of the invention, reference being had to the ring having the largest diameter, the green ring havappended claims. ing a slightly smaller diameter than the blue ring, and I claim: the red ring having the smallest diameter and the 1. In a cathode ray tube: separation increasing with the distance from the cenan evacuated envelope with a relatively small flat surter of the rings by an amount predetermined to reface at its first end and having a second end opposite said first end, said flat surface being of predetermined width which is less than approximately 3 inches;

at least one first group of a first, second and third set verse the chromatic aberration introduced at wide angles by simple, wide-angle, short focal length oculars.

2. In a cathode ray tube: an evacuated envelope with a relatively small flat surof electron-beam responsive elements on the inside face at its first end and having a second end opposite of said envelope at its said first end, each of said said first end, said flat surface being of predetermined elements being of predetermined width which is less width which is less than approximately 3 inches; than approximately the width of said flat surgroup of electron-beam-responsive elements on the face in at least one dimension and each of said first, inside of said envelope at its said first end, each of second and third set of elements having an orderly said elements being of predetermined width which is adjacent relationship with each other and all forming less than approximately & the width of said flat a predetermined number of adjacent distinct lines surface in at least one dimension and each of said elewhich is more than approximately 6,000 upon said ments having an orderly adjacent relationship with flat surface, said first, second and third elements giveach other and all forming a predetermined number ing 01f red, green, and blue light respectively when adjacent distinct lines which is more than approxirespectively energized; mately 6,000, said elements giving Off light when at least one second group of first, second and third energized;

means of projecting a respective first, second and third means for projecting an electron beam which has a electron beam which has a respective diameter of a diameter of a predetermined dimension corresponding predetermined dimension corresponding to said dito said dimension of said elements on the inside of mension of said elements on the inside of said ensaid envelope at its said second end for energizing velope at its said second end for energizing respecrespectively said elements; tively said elements of said first, second and third set vertical and horizontal deflection means intermediate of elements; said first and second ends for moving said electron at least one masking means on the inside of said enbeam over said electron-beam-responsive elements velope between said first end and said second end and at high frequencies; adjacent said first end, for allowing said first electron means connected to said vertical and horizontal deflecbeam of each said second group to strike only said tion means for generating vertical and horizontal first set of elements of its corresponding group, said scanning signal frequencies, the frequencies of the second electron beam of each said second group to signals being sufliciently high and characterized so strike only said second set of elements of its correthat the signals cause said deflection means to provide spond group, and said third electron beam of each for a predetermined number of distinct, contiguous said group to strike only said third set of elements of beam traces greater than approximately 6,000 on its corresponding group; said flat surface thereby causing this many beam revertical and horizontal deflection means intermediate sponding scan lines upon said elements in a time insaid first and second ends for moving said electron terval less than the flicker rate for the human eye; beams over said electron-beam-responsive elements means associated with said deflection means for generat high frequencies; ating additional signals which cause said deflection means connected to said vertical and horizontal deflecmeans to introduce a predetermined amount of distion means for generating vertical and horizontal tortion in the traced image which will reverse the scanning signal frequencies, the frequencies of the distortion introduced by a predetermined wide-angle signals being sufliciently high and characterized so viewing ocular. that the signals cause said deflection means to provide for a predetermined number of distinct contiguous References Clted beam traces greater than approximately 6,000 on said UNITED STATES PATENTS flat surface thereby causin this many beam responding scan lines upon said e lements in a time interval 2,864,032 12/1958 Amdursky et al less than the flicker rate for the human eye; 2907915 10/1959 Glelchauf first, second and third means associated with said de- 3028521 4/1962 Szegho 31 3 flection means for altering the respective deflection 3,059,140 10/1962 Heuer 315 13 signal acting to deflect the respective said first, second and third electron beam whereby the scanning pattern produces three separate chromatic rings with the blue RODNEY D. BENNETT, 111., Primary Examiner MALCOLM F. HUBLER, Assistant Examiner 

